dict1 = {"a":23, "b":4, "c":9, "d":3, "e":12}
# 思路
# 遍历字典,在遍历的时候,检查值是否为9,如果是9,显示9对应的键
for n in dict1:
    if dict1[n] == 9:
        print(n)  # 如果条件成立,那么就显示n,就是是值9对应的键
